Creating Server Blocks

1. Defining Server Block

Directive	Description	Example
server_name	Defines the domain name(s) for the server block	`server_name example.com www.example.com;`
listen	Specifies the port and address to listen on	`listen 80;`
root	Sets the root directory for the server block	`root /var/www/html;`
index	Defines the default file to serve	`index index.html index.htm;`

Example: Basic Server Block Configuration

server {
    listen 80;
    server_name example.com www.example.com;
    root /var/www/html;
    index index.html index.htm;

    location / {
        try_files $uri $uri/ =404;
    }
}

2. Configuring Listen Directive

Directive	Values	Description
listen	`80`	Default HTTP port
listen	`443 ssl`	HTTPS port with SSL
listen	`localhost:8080`	Listen on specific host and port
listen	`192.168.1.1:80`	Listen on specific IP and port
listen	`unix:/var/run/nginx.sock`	Unix socket for internal communication

Example: Basic HTTP server block with listen directive

server {
    listen 80;
    server_name example.com;

    root /var/www/example.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

Example: HTTPS server block with SSL listen directive

server {
    listen 443 ssl;
    server_name example.com;

    ssl_certificate /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;

    root /var/www/example.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

3. Setting Server Name

Directive	Values	Description
server_name	`example.com`	Defines the domain name(s) for this server block
server_name	`www.example.com`	Can include subdomains and wildcards like `*.example.com`
server_name	`example.com example.org`	Multiple domains can be specified in one directive

Example: Basic server_name configuration

server {
    listen 80;
    server_name example.com www.example.com;
    root /var/www/example;
    index index.html;
}

Note: The server_name directive is required for each server block to match incoming requests.

Warning: If server_name is not set, Nginx will use the first server block as default, which can lead to unexpected behavior.

4. Using Wildcard Server Names

Directive	Values	Description
server_name	`*.example.com`	Matches any subdomain of example.com
server_name	`www.*.example.com`	Matches www followed by any subdomain of example.com

Example: Wildcard server name configuration

server {
    listen 80;
    server_name *.example.com;
    root /var/www/example;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

Note: Wildcard server names can match multiple subdomains but do not support IP address wildcards.

5. Setting Default Server

Directive	Values	Description
server_name	`localhost`	Defines the server name for this block
listen	`80`	Port to listen on for HTTP requests

Example: Default Server Configuration

server {
    listen 80;
    server_name localhost;
    root /var/www/default;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

Note: The server_name directive is used to define the server name for this block. When no server_name matches a request, the default server is used.

6. Configuring Multiple Server Blocks

Example: Basic Multiple Server Blocks Setup

# /etc/nginx/sites-available/example.com
server {
    listen 80;
    server_name example.com www.example.com;
    root /var/www/example.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

# /etc/nginx/sites-available/blog.example.com
server {
    listen 80;
    server_name blog.example.com;
    root /var/www/blog.example.com;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

Directive	Description	Usage
server	Defines a server block configuration	Used to define each virtual host
listen	Specifies the port and address to listen on	`listen 80;`, `listen [::]:80;`
server_name	Defines the domain names for this server block	`server_name example.com;`
root	Defines the root directory for requests	`root /var/www/example.com;`

Note: Server blocks must be enabled by linking them to /etc/nginx/sites-enabled/ or including them in the main config.

Workflow: Enabling Multiple Server Blocks

Create a configuration file for each domain in /etc/nginx/sites-available/
Link each file to /etc/nginx/sites-enabled/ or include them in the main config
Test the configuration with nginx -t
Reload Nginx to apply changes: systemctl reload nginx

7. Setting Root Directory

Directive	Values	Description
root	`/var/www/html`	Sets the root directory for requests to the specified path.

Example: Setting Root Directory

server {
    listen 80;
    server_name example.com;
    root /var/www/example.com;
    index index.html index.htm;
}

Note: The root directive affects how Nginx resolves file paths for requests. It is important to ensure that the directory has appropriate permissions for Nginx to read files.

8. Configuring Index Files

Directive	Values	Description
index	`index.html index.htm`	Specifies the default files to serve when a directory is requested

Example: Setting Index Files

server {
    listen 80;
    server_name example.com;

    location / {
        index index.html index.htm;
    }
}

9. Using Server Name Matching

Directive	Values	Description
server_name	`example.com`	Defines the domain name(s) that this server block handles.
server_name	`www.example.com`	Matches the www subdomain for the same domain.
server_name	`example.com www.example.com`	Matches both the root and www subdomain.
server_name	`~^www\.(.*)$`	Uses regex to match any www subdomain.
server_name	`_`	Matches any hostname that does not match others.

Example: Basic server_name usage

server {
    listen 80;
    server_name example.com www.example.com;
    root /var/www/example.com;
    index index.html;
}

Example: Regex server_name

server {
    listen 80;
    server_name ~^www\.(.*)$;
    return 301 http://$1$request_uri;
}

Note: Nginx matches server blocks based on the server_name directive. The first matching block is used for handling requests.

Warning: If no server_name is specified, the server block will match any request (default server).

10. Setting Server-specific Variables

Variable	Default Value	Description	Example
server_name	`localhost`	Name of the server block	`server { listen 80; server_name example.com; }`
root	`/var/www/html`	Root directory for the server	`root /var/www/example.com;`
index	`index.html index.htm`	Default files to serve	`index index.html index.htm;`
access_log	`/var/log/nginx/access.log`	Path to access log file	`access_log /var/log/nginx/example.com.access.log;`
error_log	`/var/log/nginx/error.log`	Path to error log file	`error_log /var/log/nginx/example.com.error.log;`

Example: Setting Custom Variables

server {
    listen 80;
    server_name example.com;
    root /var/www/example.com;
    index index.html;

    access_log /var/log/nginx/example.com.access.log;
    error_log /var/log/nginx/example.com.error.log;

    location / {
        try_files $uri $uri/ =404;
    }
}

11. Understanding Server Block Selection

Criteria	Description	Behavior
server_name	`example.com`	If the request's Host header matches exactly, this server block is selected.
server_name	`www.example.com`	Matches subdomain and domain combination.
server_name	`.example.com`	Matches any subdomain of example.com (e.g., api.example.com, test.example.com).
server_name	`example.com` and `www.example.com`	Multiple names can be specified to match the same server block.
server_name	`example.com` and `example.org`	Different domains can be handled by the same server block if configured.
server_name	`example.com` and `example.org`	Each domain can be handled by a different server block if needed.

Example: Matching server_name directive

server {
    listen 80;
    server_name example.com www.example.com;
    root /var/www/example;
    index index.html;
}

Note: If no server_name matches the request, Nginx uses the first server block defined in the configuration file.

12. Implementing Catch-all Server Block

Directive	Description	Example
server_name	Defines the domain name(s) for this server block. Use `_` to match any hostname.	`server { listen 80; server_name _; return 444; }`

Example: Catch-all server block returning 444

server {
    listen 80;
    server_name _;
    return 444;
}

Note: Returning 444 closes the connection without sending a response. It's useful for blocking unwanted traffic or acting as a "black hole" for invalid hostnames.